1. Field of the Invention
This invention relates to a multi-needle embroidering machine having a plurality of needles at its head, and more particularly, to a multi-needle embroidering machine having a plurality of machine heads, and a mechanism for changing a thread to a differently colored one at each machine head.
2. Description of Related Art
FIG. 10 shows a conventional two-head multi-needle embroidering machine 50 having two juxtaposed machine heads 51A and 51B. It has a controller 52 which inputs information on a design to be embroidered, a driver unit 53 which analyzes the inputted information to prepare one-needle data as known in the art, a plurality of needles 54 of which one is selected in accordance with the one-needle data so that a particular embroidery thread may be selected, and a spindle of which the rotation is transmitted through a crank mechanism to cause the selected needle 54 to move vertically to stitch the design to be embroidered. The motion of an embroidery frame 56 which is movable in the directions X and Y along a table 55 is so controlled as to be synchronous with the vertical motion of the needle 54. A plurality of embroidery threads differing from one another in color, etc. are appropriately changed for selective use to embroider a desired pattern. The changing of the threads is effected by selecting an appropriate one from the needles 54. The two machine heads 51A and 51B are connected by two rods 57 and 58 to effect the changing of the threads simultaneously.
FIG. 11 shows a color changing mechanism employed in the embroidering machine 50 for effecting the changing of the threads. It includes a needle mounting member 59 provided with a crank mechanism, and a rotary disk 60 connected to the needle mounting member 59 horizontally rotatably. The rotary disk 60 has a plurality of appropriately spaced apart recesses 60a formed on its peripheral edge, and carries thereon a needle bar holding member 60b holding the needles vertically movably. A needle mechanism is not shown in FIG. 11. The rotary disk 60 is fitted with a bearing 61 and a sealing metal ring 62 which are fitted to the needle bar holding member 60b, a thrust bearing outer race 63, a thrust bearing 64 and a thrust washer 68 which are fitted between the needle mounting member 59 and the rotary disk 60, and a bearing 61, a thrust bearing outer race 63, a thrust bearing 64 and a lower end member 65 for a drive shaft which are fitted under the rotary disk 60. A connecting arm 66 extends radially outwardly from the rotary disk 60, and has a free end provided with a joint pin 67. The rod 58 is connected by a connecting member 71 and a holding screw 72, and is connected to the joint pin 67 by a uni-ball joint 73 and a nut 74. The rod 58 is movable to cause the rotation of the rotary disk 60.
The rotation of the rotary disk 60 is restricted by a lock lever 80. The lock lever 80 is mounted on the needle mounting member 59 by a bracket 81 to which it is rotatably attached by a shaft 82, a bolt 83 and a nut 84. The lock lever 80 has at one end thereof a projection 80a which is engageable with any of the recesses 60a of the rotary disk 60, while a rod clamp 85 is attached to the other end thereof by a nut 87. The rod 57 is movable to cause the rotation of the lock lever 80. The rod 57 is connected by a connecting member 88 and a holding screw 89, and is connected to the rod clamp 85 by a holding screw 86. The lock lever 80 is normally urged toward the needle mounting member 59 by a pin 90 and a spring 91. The drive shaft 92 extends vertically through the needle mounting member 59, and is fitted with an upper end member 93 for the drive shaft. The needle unit as a whole (not shown) is rotatable about the drive shaft 92.
As long as a selected needle continues its vertical motion to make stitches, the projection 80a remains in engagement with one of the recesses 60a, and the rotary disk 60, therefore, remains locked against rotation. When it has become necessary to change the needle to feed a differently colored thread, a needle changing motor and a solenoid installed behind the controller 52, though not shown, are driven to move the rod 57 and rotate the lock lever 80 to unlock the rotary disk 60, as well as moving the rod 58 by an appropriate distance to rotate the rotary disk 60 to an appropriate extent. Upon completion of the rotation of the rotary disk 60, the lock lever 80 is rotated in the opposite direction to engage its projection 80a with another recess 60a and thereby lock the rotary disk 60 again. The appropriate selection of the needles is repeated to effect the necessary changing of differently colored threads. The rods 57 and 58 are connected to the rotary disks 60 and the lock levers 80 in both of the machine heads 51A and 51B, so that the two machine heads 51A and 51B may effect the simultaneous selection of similar needles for changing the threads.
The needle changing motor and solenoid employed in the conventional multi-needle embroidering machine for driving the rods 57 and 58 to change the embroidery threads are installed near the controller 52 at one end of the table 55. The table 55 has to be sufficiently large to enable the controller 52 to allow the free movement of the embroidery frame 56 throughout any embroidering operation, and the rods 57 and 58 have, therefore, to be sufficiently long. The rods 57 and 58 have to be so long as to bring about a number of problems, as pointed out below:
(1) The rods 57 and 58 vibrate heavily, and cause the needle bars and thereby the needles to vibrate so heavily that threads are easily broken; PA1 (2) The vibration of the rods 57 and 58 makes a large noise which worsens the environment in which the machine is used; and PA1 (3) The rods 57 and 58 hinders work, particularly on the table 55 in the area which is farther than the rods.